1. Field
This disclosure relates generally to radio frequency transmitters, and more specifically, to a radio frequency transmitter having an amplifier with power supply modulation.
2. Related Art
Power amplifiers, such as the ones used in cellular radio frequency transmitters, must satisfy key metrics, including output power, DC-RF efficiency, and linearity. These competing metrics have forced power amplifier designers to use different types of amplifiers, including Doherty amplifiers. The use of basic Doherty amplifiers has resulted in realizing some improvements in key metrics that are demanded by 3G and 4G systems, but further improvements are needed. This is because incremental improvements in metrics, such as the DC-RF efficiency of such amplifiers are needed.
Accordingly, there is a need for improved power amplifiers, including a radio frequency transmitter having an amplifier with power supply modulation.